The Duke of Cambridge has spoken about the online pressures young women face to look their best and warned about the "fakeness" of the cyber world.
William criticised the growing problem of "touched up" pictures during an unannounced visit to a west London academy to discuss cyber bullying and mental health issues at a special school assembly.
He was joined by mental health campaigner rapper Professor Green who in the past has supported the duke's Heads Together campaign to encourage the nation to talk about their psychological problems.
After a question and answer session hosted by YouTuber Dan Howell, William and Green had the chance to talk to groups of year 10 students who had listened to the earlier assembly that highlighted the issues around cyber bullying.
When the chat turned to online images the duke told Samara Hackett-Valton and Sophie Crowder, both aged 15, from Burlington Danes Academy in White City: "It's the best pictures or the touched up pictures, particularly the girls.
"I worry for you girls ... so don't try and recreate or think that's what, you know, you've got to aim for - there's a lot of fakeness online so don't worry about that."
There is a growing market for apps that allow users to touch-up their selfies or online pictures removing blemishes and making images flawless, but celebrity photographs that have been manipulated are regularly featured on the web.
William said that he and Green did not have to grow up with the online influences the pupils now face, and there were no smartphones when he was younger.
The duke said: "The online world is a whole new sphere that we never had to deal with, if you're trying to do your normal life and trying to get that right and make friends.
"Then you'll also try and do that online, that's a lot of pressure guys."
Sophie said after meeting the duke that the pressures he described of presenting a perfect online image was something she had experienced: "I've done my hair, I've done my make-up before going online, I'm just as guilty.
"You make an effort, when you're on Snapchat and you've got 50 followers - they're not your best friends as you've never met them - but still you don't want them to see you after you've just got out of bed."
Samara added: "I take hundreds of pictures and delete them all because they're not what I want.
"It's because of the celebrities, if they posted pictures of themselves just out of bed that would make a huge difference."